U.S. patent application number 09/953648 was filed with the patent office on 2002-01-17 for crown reinforcement for a radial tire.
Invention is credited to Royer, Thierry, Suarez, Fernando.
Application Number | 20020005239 09/953648 |
Document ID | / |
Family ID | 9543382 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020005239 |
Kind Code |
A1 |
Royer, Thierry ; et
al. |
January 17, 2002 |
Crown reinforcement for a radial tire
Abstract
An aircraft tire, having a radial carcass reinforcement
surmounted radially to the outside by a crown reinforcement and a
tread, said crown reinforcement including: a) at least one ply of
reinforcement elements of high modulus oriented circumferentially,
b) two plies having ends free of reinforcement elements of high
modulus, which are parallel to each other within each ply and are
crossed from one ply to the next, forming with the circumferential
direction an angle .alpha., of between 5.degree. and 35.degree.,
and c) radially to the outside, an assembly of at least two layers
of textile elements of low modulus which are oriented relative to
the circumferential direction at an angle .beta., of between
0.degree. and 35.degree., said two layers being obtained by winding
in a zigzag a strip, formed of at least one coated cable, and the
assembly of the layers having an axial width greater than the width
of the tread, whereas the widths of the textile plies of high
modulus are less than said width of the tread.
Inventors: |
Royer, Thierry; (La Roche
Blanche, FR) ; Suarez, Fernando; (Menetrol,
FR) |
Correspondence
Address: |
BAKER & BOTTS
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
|
Family ID: |
9543382 |
Appl. No.: |
09/953648 |
Filed: |
September 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09953648 |
Sep 17, 2001 |
|
|
|
PCT/EP00/01318 |
Feb 17, 2000 |
|
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Current U.S.
Class: |
152/560 |
Current CPC
Class: |
B60C 9/263 20130101;
Y10T 152/10765 20150115; B60C 9/2204 20130101; Y10T 152/10801
20150115; Y10T 152/10783 20150115; B60C 2200/02 20130101; B60C
9/2009 20130101 |
Class at
Publication: |
152/560 |
International
Class: |
B60C 009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 1999 |
FR |
99/03415 |
Claims
We claim:
1. An aircraft tire, comprising a radial carcass reinforcement
surmounted radially to the outside by a crown reinforcement and a
tread, characterized in that said crown reinforcement comprises: a)
at least one ply of textile reinforcement elements oriented
circumferentially, the secant modulus of extension of an element
being at least equal to 200 cN/tex b) at least two plies of textile
reinforcement elements having ends free of textile reinforcement
elements, which elements are parallel to each other within each ply
and are crossed from one ply to the next, forming with the
circumferential direction an angle .pi., of between 5.degree. and
35.degree., the secant modulus of extension of an element being at
least equal to 200 cN/tex, and c) radially to the outside, an
assembly of at least two layers of textile reinforcement elements
oriented relative to the circumferential direction at an angle
.beta., of between 0.degree. and 35.degree., the secant modulus of
extension of an element being at most equal to 200 cN/tex, and said
two layers being obtained by winding a strip, formed of at least
one element coated with rubber mix, from one edge of said layers to
the other, the assembly of said layers having an axial width
greater than the width of the tread, the widths of the plies formed
of textile elements of high modulus being less than said width of
the tread.
2. A tire according to claim 1, characterized in that the layers of
textile elements, the secant modulus of extension of an element of
which is at least equal to 200 cN/tex, are layers of elements of
aromatic polyamide.
3. A tire according to one of claim 1, characterized in that the
layers of textile elements, the secant modulus of which is at most
equal to 200 cN/tex and which are obtained by winding from one edge
to the other, are formed of cables of aliphatic polyamide.
4. A tire according to claim 1, characterized in that the at least
one ply of circumferential elements is located radially on the
carcass reinforcement.
5. A tire according to claim 4, characterized in that the at least
one ply of circumferential elements is obtained by helical winding
of a strip formed of at least one reinforcement element of aromatic
polyamide, said element being coated with suitable rubber mix.
6. A tire according to claim 1, characterized in that the plies
formed of elements oriented at the angle .alpha., radially above
the at least one ply of circumferential elements, have axial widths
which differ from each other but which are greater than the width
of plies of said at least one ply of circumferential elements while
remaining less than the width of the tread.
7. A tire according to claim 2, characterized in that the assembly
of layers of elements, the modulus of which is at most equal to 200
cN/tex and which are oriented relative to the circumferential
direction at an angle .beta., has an axial width such that the
edges of said assembly are coupled to the carcass reinforcement
over a developed length 1 at least equal to 20 mm.
Description
BACKGROUND OF THE INVENTION
[0001] This is a continuation of pending PCT/EP00/01318, filed Feb.
17, 2000.
[0002] The invention relates to a tire, intended to bear heavy
loads and be inflated to very high pressure, greater than 12 bar,
such as for example an aircraft tire.
[0003] A tire which meets the above criteria has been used for a
long time is composed of a radial carcass reinforcement, formed of
one or more plies of textile reinforcement elements, which plies
are generally divided into two groups: a first group, referred to
as axially inner plies, which are anchored within each bead to at
least one bead wire by winding around said bead wire, from the
inside to the outside to form ply upturns; and a second group
referred to as axially outer plies, the radially inner ends of
which are generally arranged within each bead beneath the bead
wire. Said radial carcass reinforcement is radially surmounted by a
crown reinforcement formed of a plurality of layers of textile
reinforcement elements which are inclined relative to the
circumferential direction by a certain angle a. So as to avoid the
free ends of crown plies, said layers are obtained by winding,
around a form, whether cylindrical or rounded, or a carcass
reinforcement blank, a strip of at least one textile reinforcement
element from one edge of the layer to the other, forming the
desired angle with the equatorial plane.
[0004] The textile elements commonly used are of aliphatic
polyamide, and have relatively poor tensile strength
characteristics, which is why numerous plies are used. As for
numerous tires, the use of aromatic polyamide or other similar
material as material for reinforcing the crown reinforcement may
prove advantageous in an aircraft tire, owing to the properties of
said material. However, it is not easy to use such a material, and
its use has numerous problems. For example, it is virtually
impossible to use it in a crown reinforcement such as described
above, obtained by winding a strip in a zigzag: the curvatures
adopted by the strip, and hence by the reinforcement elements at
the edge of the layer, impart to said elements very major tensions
and compressions which, combined with the fact that the aromatic
polyamide has resistances to said stresses which deteriorate with
temperature, cancel out all the advantages of the aromatic
polyamide.
[0005] A crown reinforcement, with plies, the edges of which are
folded over on themselves, is also scarcely conceivable owing to
the curvatures and adhesion to the rubber which is inferior to that
of an aliphatic polyamide.
SUMMARY OF THE INVENTION
[0006] The object of the invention is to permit the use of aromatic
polyamide as material for the main reinforcement elements of a
crown reinforcement, by adapting the architecture of said
reinforcement to the material.
[0007] The aircraft tire according to the invention, comprising a
radial carcass reinforcement surmounted radially to the outside by
a crown reinforcement and a tread, is characterized in that said
crown reinforcement is composed:
[0008] a) of at least one ply of textile reinforcement elements
oriented circumferentially, the secant modulus of extension of an
element being at least equal to 200 cN/tex
[0009] b) of at least two plies having ends free of textile
reinforcement elements, which are parallel to each other within
each ply and are crossed from one ply to the next, forming with the
circumferential direction an angle a, of between 5.degree. and
35.degree., the secant modulus of extension of an element being at
least equal to 200 cN/tex, and
[0010] c) radially to the outside, of at least two layers of
textile reinforcement elements oriented relative to the
circumferential direction at an angle .beta., of between 0.degree.
and 35.degree., the secant modulus of extension of an element being
at most equal to 200 cN/tex, and said two layers being obtained by
winding a strip, formed of at least one element coated with rubber
mix, from one edge of said layers to the other, the assembly of
said layers having an axial width greater than the tread width,
whereas the widths of the plies formed of textile elements of high
modulus are less than said tread width.
[0011] "Width of the tread" is to be understood to mean the width,
measured in the radial plane of the axis of the fitted wheel, of
the contact surface between the tire mounted on its operating rim,
inflated to the recommended pressure and bearing its standardised
load.
[0012] "Circumferentially oriented elements" is to be understood to
mean elements forming with the circumferential direction angles
which may be between 0.degree. and 10.degree..
[0013] The secant modulus of extension M.sub.a of a reinforcement
element is calculated for the assemblies in accordance with the
equation:
M.sub.a=F/.epsilon..multidot.1/T.sub.i
[0014] with F: force to which the assembly is subjected for a
relative elongation of 4%,
[0015] .epsilon.: the relative elongation, equal to 4%,
[0016] Ti: linear density, expressed in Tex, of the assembly.
[0017] An element having a secant modulus greater than 200 cN/tex
is referred to as an element of high modulus.
[0018] Preferably, the ply (plies) of circumferential elements is
(are) directly located on the carcass reinforcement, and is (are)
obtained by helical winding of a strip formed of at least one
reinforcement element of aromatic polyamide, said element being
coated with suitable rubber mix.
[0019] The plies formed of elements oriented at the angle .alpha.,
radially above the ply (plies) of circumferential elements, are
also preferably formed of cables of aromatic polyamide and have
axial widths which differ from each other but which are greater
than the width(s) of said plies of circumferential elements while
remaining less than the width of the tread.
[0020] All of the layers of the textile elements, having a modulus
at most equal to 200 cN/tex, may be formed of cables of aliphatic
polyamide, which are oriented relative to the circumferential
direction at an angle .beta., or of what are called hybrid cables,
for example cables formed of two cords of aromatic polyamide and
one cord of aliphatic polyamide, oriented in the same manner. Said
assembly will preferably have an axial width such that the edges of
said assembly are coupled to the carcass reinforcement over a
developed width at least equal to 10% of said axial width. "Edge
coupled to the carcass reinforcement" is to be understood to mean
an edge in contact over a certain length with said reinforcement
and separated from said reinforcement by a thickness of rubber
equal to the total of the greater and lesser thicknesses
respectively of the calendering layers of the final carcass
reinforcement ply and the layer of the assembly in contact with
said final ply. The above variant permits a distinct improvement in
the endurance of the crown reinforcement from the point of view of
inter-ply separations, and also higher speed, while permitting an
increase in the bursting pressure of the tire, as well as better
uniformity of said tire, in particular from the cyclic point of
view, which minimizes abnormal tread wear.
[0021] As is known per se, and although in the case of small
dimensions the assembly of the layers of the reinforcement elements
of a modulus at most equal to 200 cN/tex may advantageously play
the role of protective layers, the crown reinforcement thus claimed
will be advantageously finished off by at least one protective ply
formed of metallic elements which undulate in the plane of the ply,
said ply being located radially to the outside of the assembly of
the layers of cables of aliphatic polyamide.
[0022] The invention will be more fully understood with reference
to the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows, viewed in meridian section, an aircraft tire
according to the invention; and
[0024] FIG. 2 shows a preferred variant of said tire.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0025] The example described is that of a tire of standardized
dimension 29.times.7.7 R 15 (standards of the Tire and Rim
Association). The carcass reinforcement 1 is formed of three plies
1A to 1C of radial textile cables. "Radial cables" is to be
understood to mean cables forming with the circumferential
direction of the tire angles which may be within the range
90.degree..+-.10.degree.. Of these three plies, two axially inner
plies 1A, 1B are wound within each bead around a bead wire 2
having, in the case in question, a circular cross-section and being
coated with a layer 20 of rubber mix of high modulus of elasticity
in tension, from the inside to the outside of the tire P to form
upturns 10A, 10B.
[0026] The section of the bead wire 2 is surmounted radially to the
outside by a profiled element or filler 12 of elastomeric mix
having substantially the form of a triangle, the apex A of which,
which is radially farthest from the axis of rotation of the tire,
is located at a distance D from the straight line XX', firstly
parallel to said axis of rotation and secondly passing through the
geometric center O of the circle circumscribed on the cross-section
of the bead wire 2, which circle, in the case described, is
identical to the section itself.
[0027] The upturns 10A, 10B of the inner carcass plies 1A, 1B have
their ends radially distant from the straight line XX' by amounts
greater, in the case in question, than the distance D.
[0028] The same applies to the radial end of the axially inner
strand 110 of the tongue 11, which is composed of radial textile
cables identical to the cables of the carcass plies (but which may
be different therefrom). As for the radial end of the axially outer
strand 111 of the inner tongue 11, it is separated from the
straight line XX' by a radial distance less than the distance
D.
[0029] The so-called outer carcass ply 1C covers, axially to the
outside, the upturns 10A, 10B of the inner carcass plies 1A and 1B.
The ply 1C is wound around the bead wire 2 over a circular portion
or arc corresponding to an angle at the center of the circle
circumscribed on the bead wire 2 which is at most equal to
180.degree., such that the end of this ply 1C is located radially
beneath the reference straight line XX'.
[0030] The tire bead is finished off, as is known per se, by the
sidewall mix 5 and bead protection mix 6, whereas an inner layer 7
forms the inner wall of the tire.
[0031] Said carcass reinforcement 1 is surmounted radially by a
crown reinforcement 3 of textile cables. This crown reinforcement 3
is formed radially from the inside to the outside by
[0032] a) a twin ply 30 composed of two plies 300 and 301 of
330.times.2 textile cables of aromatic polyamide which are arranged
circumferentially, each ply being obtained by the helical winding,
on the carcass reinforcement blank 1, of a cable coated with
rubber, and the respective widths of said two plies 300 and 301
being 95 mm and 85 mm, less than the width L of the tread 4
measured as described above and equal to 130 mm;
[0033] b) radially above, a twin ply 31 composed of two plies 310
and 311 which are cut or have free ends, each of said plies 310 and
311 being formed of 167.times.3 textile cables of aromatic
polyamide, said cables being parallel to each other within each ply
and crossed from one ply to the next, forming with the
circumferential direction an angle a equal to 24.degree., said
plies 310 and 311 having a total thickness of 3.0 mm, and having
widths which firstly are unequal and secondly are such that they
axially cover the twin ply 30 radially underneath, while remaining
less than the width L of the tread 4;
[0034] c) radially to the outside, an assembly 32 composed of two
angled layers, obtained by winding a strip of 8 textile cables of
aliphatic polyamide from one edge of the assembly 32 to the other,
forming an angle .beta. of 10.degree. with the circumferential
direction, said angle being linked physically on one hand to the
number of periods of formation of the assembly 32, and on the other
hand to the developed width of said assembly which is far greater
than the tread width L since it is equal to 190 mm.
[0035] Whereas the edges of the assembly 32 lie radially, in the
tire which is shown in FIG. 1, on a complex of rubber mixes such
that the rubbers 81 axially extending the twin ply 31, the profiled
elements 82 separating the twin ply 31 from the twin ply 30 and
extending said twin ply 30 and the profiled elements 83 separating
the carcass reinforcement 1 from the crown reinforcement 3, said
edges are, in the example of a tire which is shown in FIG. 2, in
direct contact, over a certain developed length 1, at least equal
to 20 mm and in the case described equal to 30 mm, with the carcass
reinforcement 1, the thickness of rubber separating the cables of
the radially lower layer of the assembly 32 from the cables of the
carcass ply 10C being the total of the thickness of the calendering
layer which internally covers the cables of the layer 32 and the
thickness of the calendering layer which externally covers the
final carcass ply 10C. Edge rubbers and rubber profiled elements,
forming an assembly 8, fill the space thus created between the
carcass reinforcement 1 and the assembly 32.
* * * * *